Does exposure to maternal smoking during pregnancy affect the clinical features of ADHD? Results from a controlled study

Objectives. Exposure to maternal smoking during pregnancy may be a signifi cant risk factor for attention-deficit/hyperactivity disorder (ADHD) independently of family history of ADHD. The main aim of this study was to examine whether the clinical profile of ADHD differs between children with and without exposure to maternal smoking during pregnancy. Methods. This was a case-control study of boys and girls with and without ADHD ascertained from psychiatric and paediatric sources. Maternal smoking during pregnancy was defined by interviews with subjects' mothers. Main outcome measures were ADHD symptoms and associated clinical features in children with and without exposure to maternal smoking during pregnancy. Results. No signifi cant differences were found between ADHD children with and without exposure to maternal smoking during pregnancy on clinical characteristics. When these analyses were repeated in the subgroup of subjects without parental history of ADHD, there were also no statistically signifi cant differences found. Conclusions. Despite adequate statistical power, no signifi cant differences were found between ADHD children with and without exposure in the clinical features of ADHD and associated disorders. Results provide support for the notion that ADHD cases resulting from exposure to maternal smoking during pregnancy have similar clinical profiles as other ADHD cases.